The present invention pertains generally to electrical connectors for electrically connecting the contacts of a first component to the contacts of a second component. More specifically, the present invention pertains to high density, miniature electrical connectors. The present invention is particularly, but not exclusively, useful as a miniature connector with an array of closely spaced conductors suitable for either compression or solder connection with circuit boards or their components.
Electrical connectors can be used to connect one electronic component such as a microprocessor to another electronic component such as a printed circuit board. In modern equipment, electrical connectors capable of simultaneously connecting large numbers of electrical circuits from one electronic component to another are often required. Typically, for such an application, the electrical connector includes a frame having two opposed contact surfaces. Each contact surface on the connector is provided for engagement with a corresponding contact surface on one of the electronic components. The connector frame functions to both hold the midsections of a plurality of individual electrical conductors, and to electrically isolate each conductor from the remaining conductors. Also, the frame generally incorporates features for mechanically attaching the electronic components to one another. Heretofore, connectors having conductors that are molded-in-place within the frame have been widely used. In these connectors, each conductor has a first finger that projects from one side of the frame and a second finger that projects from the other side of the frame. The midsection of each conductor connects the first finger to the second finger.
A typical mold-in-place conductor is manufactured by first stamping an array of conductors from a sheet of metal. Generally, the conductors are stamped with the flat midsection of each conductor remaining essentially in the plane of the original sheet, and the fingers of the conductor projecting from the plane of the original sheet. Next, the array of conductors is placed in a mold and molten plastic is injected into the mold cavity to mold the midsections of each conductor in place and to create a frame having opposed contact surfaces. The result is a connector having the flat midsection of each conductor oriented substantially parallel to the contact surfaces of the frame. These mold-in-place conductors have established an excellent reputation for reliability throughout the electronics industry. Specifically, these connectors provide an acceptable signal to ground ratio with little or no measurable crosstalk between conductors.
In modern equipment, electronic components have become increasingly miniaturized, while the number of circuits in each electronic component has multiplied. These effects have combined to require smaller connectors having smaller spacings between adjacent conductors. Unfortunately, for mold-in-place connectors, small spacings between adjacent conductors are not readily obtainable when the conductor midsections are oriented parallel to the contact surfaces of the frame.
In addition to close conductor spacing, connectors that have long fingers are generally prescribed to provide for good wiping action with the land of the electronic component. In typical mold-in-place conductors manufactured by the process described above, small spacings between conductors are generally unobtainable when long fingers are prescribed. Specifically, this occurs because during stamping, the fingers are formed between midsections of adjacent conductors, and the spacing between adjacent midsections is maintained between the stamping and the molding steps. Consequently, in typical mold-in-place conductors manufactured by the process described above, an increase in finger length generally must be accompanied by an increase in spacing between adjacent conductors.
Another common method of manufacturing connectors, called stitching, involves molding a plastic frame containing a plurality of apertures, and then xe2x80x9cstitchingxe2x80x9d the individual contacts into the apertures of the solid frame. Generally, the conductor midsections can be oriented in the frame perpendicular to the contact surface of the frame. Consequently, close spacing between conductors is generally not limited by midsection orientation. However, stitched connectors have different performance characteristics than mold-in-place connectors and have not established industry wide acceptance. For example, the presence of a large number of apertures within the frame affects both the electrical characteristics and the structural capabilities of the frame.
In light of the above, it is an object of the present invention to provide an electrical connector having hundreds of reliable mold-in-place conductors spaced at less than 1.5 mm from each other. Another object of the present invention is to provide a connector having relative dimensions, such as the dimensional relationship between the spacing between adjacent conductors and the length of each conductor finger, that are not constrained due to the orientation of the midsection in the frame. Yet another object of the present invention is to provide electrical connectors which are easy to use, relatively simple to manufacture and comparatively cost effective.
The present invention is directed to an electrical connector for electrically connecting a plurality of contact lands on a first component to a plurality of contact lands on a second component. The electrical connector includes a plurality of electrical conductors, each conductor partially embedded in a molded frame made from a dielectric material.
The frame is formed with a first side having a plurality of substantially coplanar first surfaces. Further, the first side is formed with a plurality of parallel first channels, with each first channel positioned between a pair of coplanar first surfaces. Consequently, the first side is composed of a plurality of first surfaces and a plurality of first channels. Additionally, the frame is formed with a second side opposed to the first side. The second side also has a plurality of substantially coplanar second surfaces. The frame is constructed with the second surfaces of the second side substantially parallel to the first surfaces of the first side. Like the first side, the second side is also formed with a plurality of parallel second channels, with each second channel positioned between a pair of coplanar second surfaces.
Each channel is formed with a first wall, a second wall and a bottom. Further, the walls and bottom of each channel are substantially flat. The first wall extends from a surface of the side to the bottom of the channel. Further, the first wall is substantially perpendicular to both the surface of the side, and to the bottom of the channel. Consequently, the bottom of the channel is substantially parallel to the surface of the side. Similarly, the second wall extends from a surface of the side to the bottom of the channel, and the second wall is substantially perpendicular to both the surface of the side and the bottom of the channel.
Each channel defines an axis plane. Specifically, the axis plane of each channel is parallel to the walls of the channel and is located generally midway between the walls of the channel. For the first side of the frame, each first channel defines a first axis plane. Similarly, for the second side of the frame each second channel defines a second axis plane.
Each conductor includes a first finger, a second finger and a midsection connecting the first finger to the second finger. The midsection of each electrical conductor is fully encapsulated by the frame. Preferably, the midsections of each electrical conductor are substantially flat. In the preferred embodiment, the midsection of each electrical conductor is molded in place within the frame with the flat midsection oriented perpendicular to both the first surface of the first side, and also, the first axis plane of each first channel.
Each finger is formed with a tip. Preferably, the first finger of the electrical conductor extends from the bottom of a first channel and into the first channel. Further, each first finger extends from the first side of the frame to the tip of each first finger. Similarly, in the preferred embodiment, the second finger of the electrical conductor extends from the bottom of a second channel and into the second channel. Like the first fingers, each second finger also extends from the second side of the frame to a tip of each second finger.
Additionally, the conductors are oriented within the frame with the tip of each first finger lying in a first axis plane and the tip of each second finger lying in a second axis plane. Consequently, a single conductor extends into both a first channel having a first axis plane and a second channel having a second axis plane. Stated differently, each single conductor shares a first channel and a second channel. In one embodiment of the present invention, the shared first and second channels are aligned. For purposes of the present disclosure, two channels are aligned if the axis plane of the first channel is coplanar with the axis plane of the second channel. In another embodiment of the present invention, the shared first and second channels are laterally offset. Specifically, for purposes of the present disclosure, two channels are laterally offset if the axis plane of the first channel is separated from the axis plane of the second channel by a nonzero distance.
Each finger may be shaped to facilitate electrical connection with the contact lands of a mating electronic component. In one embodiment of the present invention, the finger can be shaped for compression connection with a contact land of a component. In this embodiment, the finger is curved from the bottom of the channel to the tip of the finger. A curled contact surface is provided at or near the tip of the finger for contact with the land of a component. Specifically, the finger is curved to allow the contact surface on the finger to extend slightly beyond the surface of the frame. In other words, the finger is curved such that the distance between the contact surface on the finger and the bottom of the channel is slightly greater than the distance between the surface of the frame and the bottom of the channel. This configuration allows the contact land of a component to compress the finger of the conductor whenever the contact land is seated onto the surfaces of the frame. Alternatively, the contact surface of the finger can be dimensioned to bridge a VIA hole on a printed circuit board. In another embodiment of the present invention, the finger is shaped to allow the finger to be surface mount soldered to a contact land of a component. In this configuration, the finger is shaped such that a portion of the finger near the tip is approximately parallel to the surface of the side. Alternatively, vertical fingers can make an electrical connection to the contact ball of a ball grid array, or parallel shaped fingers could be soldered to the contact ball of a ball grid array.
Importantly, in the connector of the present invention, the conductors can be closely spaced. In particular, two conductors each having their respective first fingers in a single first channel can be spaced less than 1.5 mm apart. Specifically, the flat midsections of the conductors can be spaced less than 1.5 mm apart. Further, the connector of the present invention allows for fingers having curvelengths exceeding 1.5 mm while maintaining midsection spacings at less than 1.5 mm. For purposes of the present disclosure, the curvelength of a finger is the distance measured along the finger from the bottom of the channel to the tip of the finger.